The invention concerns an instrument of pocket size for use by anybody for reliable recognition of features of authenticity of banknotes and other security documents.
The increasing prevalence of money forging, especially because of the highly accurate color fidelity of color copiers, creates a demand for the improved recognition of forgeries in the daily handling of banknotes. The various well-known large banknote test instruments, which are designed as table instruments dependent on the electricity network, have little mobility and operate by the optical or electrical measurement of certain parameters of banknotes. It is, therefore, desirable to create a handy pocket instrument, which is suitable for use by everybody and is also suitable for carrying around every day.
A hand instrument for the recognition of forged banknotes is, however already known (EP-A-0 543 058). This instrument has the shape of a pocket torch, which should radiate light within the wave length limits of 100 to 500 nm, so as to illuminate the banknotes and to stimulate fluorescent dyes present in the banknotes to reflect. However, in shops with bright neon lighting or in daylight, testing of banknotes with this known instrument can hardly be possible. A pure fluorescence test does not seem satisfactory either.